[jira] [Created] (KAFKA-3905) remove null from subscribed topics in KafkaConsumer#subscribe

[Xing Huang (JIRA)]

Xing Huang created KAFKA-3905:
---------------------------------

             Summary: remove null from subscribed topics  in 
KafkaConsumer#subscribe
                 Key: KAFKA-3905
                 URL: https://issues.apache.org/jira/browse/KAFKA-3905
             Project: Kafka
          Issue Type: Wish
          Components: clients
    Affects Versions: 0.10.0.0
            Reporter: Xing Huang
            Priority: Minor


Currently, KafkaConsumer's subscribe methods accept Collection<String> as 
topics to be subscribed, but a Collection may have null as its element. For 
example
{code}
            String topic = null;
            Collection<String> topics = Arrays.asList(topic);
            consumer.subscribe(topics)
{code}
When this happens, consumer will throw a puzzling NullPointerException:
{code}
        at org.apache.kafka.common.utils.Utils.utf8Length(Utils.java:245)
        at org.apache.kafka.common.protocol.types.Type$6.sizeOf(Type.java:248)
        at 
org.apache.kafka.common.protocol.types.ArrayOf.sizeOf(ArrayOf.java:85)
        at org.apache.kafka.common.protocol.types.Schema.sizeOf(Schema.java:89)
        at org.apache.kafka.common.protocol.types.Struct.sizeOf(Struct.java:244)
        at 
org.apache.kafka.common.requests.RequestSend.serialize(RequestSend.java:35)
        at 
org.apache.kafka.common.requests.RequestSend.<init>(RequestSend.java:29)
        at 
org.apache.kafka.clients.NetworkClient$DefaultMetadataUpdater.request(NetworkClient.java:616)
        at 
org.apache.kafka.clients.NetworkClient$DefaultMetadataUpdater.maybeUpdate(NetworkClient.java:639)
        at 
org.apache.kafka.clients.NetworkClient$DefaultMetadataUpdater.maybeUpdate(NetworkClient.java:552)
        at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:258)
        at 
org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.clientPoll(ConsumerNetworkClient.java:360)
        at 
org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:224)
        at 
org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:192)
        at 
org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:163)
        at 
org.apache.kafka.clients.consumer.internals.AbstractCoordinator.ensureCoordinatorReady(AbstractCoordinator.java:179)
        at 
org.apache.kafka.clients.consumer.KafkaConsumer.pollOnce(KafkaConsumer.java:970)
        at 
org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:934)
{code}
Maybe it's better to remove null when doing subscription.



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